Abstract: Palmer's "subjectivity barrier" seems to be erected on a
popular but highly suspect conception of visual experience, and his "color
room" argument is invalid.

Palmer beautifully articulates a view that many philosophers and psychologists
have found compelling: in attempting to understand the mind, scientists face an
impenetrable "subjectivity barrier", behind which lies the "nature of [our]
experiences themselves" (sect. 2.1, para. 11).[1] And although Palmer sometimes sweetens the pill with such
locutions as "scientists would never know with certainty" (sect. 2.1, para.
1), and "it may not be possible to be sure" (sect. 2.2, para. 3), it
is perfectly clear that the conclusions of his arguments are--setting
futuristic brainometers aside--that we (not just "behavioral
scientists") have absolutely no reason to believe (not just no
"objective knowledge") that others have experiences with the same "intrinsic
qualities" as our own, or even that they have any experiences at all (sect.
2.5, para. 8). Thus, what might seem at first glance a sober essay curbing
the pretensions of science to explain consciousness is in fact a radically
skeptical manifesto.

According to Palmer, we can at best know about the relational structure of
others' experiences--the similarities and differences they bear to each other.
(For brevity's sake I shall ignore his further claim that we cannot know that
others have experiences.) Skepticism follows because Palmer holds that fixing
this relational structure does not fix the "sensory qualities" of
experiences.

Palmer's main examples of a difference in sensory quality with no difference in
relational structure are variants of the usual "spectrum inversion" case
(Shoemaker 1981). No doubt some commentators will attack Palmer's argument by
disputing that our color space is as symmetric as Palmer makes it out to be.
But this response does not dig deep enough, because on Palmer's conception
there may well be sensory qualities "alien" to an individual that could occupy
the relational structure of his experiences.

A potentially more promising response disputes Palmer's crucial claim that
sensory qualities can vary independently of relational structure. This response
subdivides into two: the first agrees with Palmer that interpersonal
comparisons of sensory qualities make sense (Clark 1993; Hilbert &
Kalderon, in press), while the second denies that they do (Stalnaker, in
press).[2]

As I am unconvinced that the response just mentioned can be made to work, I
shall try a different tack, and present a natural conception of visual
experience on which it is hard to get Palmer's skeptical worries going.[3]

Imagine seeing a red object--the proverbial ripe tomato. Focus your attention
on the salient property of the tomato that it shares with cherries and
strawberries. That property is redness, right? And of course red objects--like
tomatoes and cherries--look more similar, in respect of color, to orange
objects than they do to green objects. These similarity relationsamong colored objects induce corresponding similarity relations
among our experiences of color, rather than the other way around. It's
not true that red objects are more similar to orange objects than they are to
green objects because our experiences of red objects are more similar to
our experiences of orange objects than they are to our experiences of green
objects. Rather, the explanation goes the other way: our experiences are
similar because the objects of the experiences are similar. This is
because when a person has a visual experience he is only aware of what
visually appears to him, or of what his experience represents: as it
might be, the presence of a red tomato. He is not aware (at least, not without
further effort) of his experience. And similarly with the "nature of the
experiences themselves": the perceived nature of the objects of
perception (e.g. the redness of the tomato) explains the nature of
perceptions of objects. If a person has a visual experience that
represents the tomato as being red, then nothing else needs to be added
to his experience for it to have the distinctive "sensory quality of redness"
(sect. 2.1, para. 3) that Palmer thinks is hidden from scientific
enquiry. Therefore, since there appears to be no special problem about
knowing whether objects visually appear red to people, there's no special
problem about knowing the nature of others' visual experiences, and thus there
is no "subjectivity barrier".

Palmer may have been seduced by the following perennially appealing argument
for thinking that something else needs to be added to a visual experience that
represents something as red, in order for it to have the "sensory quality of
redness". Imagine having a "red" afterimage. Perhaps unreflectively you would
be inclined to call the distinctive property of the image "red", but surely the
image can't really be red--red is a property of physical objects like
tomatoes, not "mental objects" like images. So call the property of the image
"R" instead. But obviously R is present when you see red objects, like ripe
tomatoes. And since "mental objects" like images can have R, it doesn't seem
likely that R can ever be a property of a physical object like a tomato. So
when you see that a tomato is red, you are aware that the tomato is red
and that some image-like thing has R. It is the presence of an R-image
that gives your experiences of red objects (and certain afterimages) their
distinctive "sensory quality"; similarly, the distinctive sensory quality of
your experiences of green objects is due to the presence of a G-image. And now,
of course, the question naturally arises whether others' experiences of red
objects are in fact attended by G-images rather than R-images.

As tempting as this reasoning is, it is wrong. If R is to explain the sensory
quality of your experience of a ripe tomato then it is not sufficient that the
experience involve an image that has R: it must visually appear to
you that the image has R (imagine that even though the image has R, it
appears to have G: in that case you would have an experience with the
sensory quality distinctive of your experiences of green objects). But now the
alleged fact that the image has R isn't doing any explanatory work: the
sensory quality of your experience is solely explained by the fact that it
appears to you that the image has R, irrespective of whether the image has
R. So the introduction of R was an idle wheel--redness would do the job
just as well. Your afterimage experience was a kind of hallucination: it
visually appeared to you that something was red (that's what gave your
experience its distinctive sensory quality), but nothing in the scene
before your eyes was red (that's why it was a kind of hallucination). Further,
although it seemed to you that there was an image floating before your eyes, in
fact there was no object--not even a mental one--there at all.

Finally, as has been pointed out numerous times (e.g. Copeland 1993), the
Chinese room argument is fallacious. The conclusion concerns the system
(it can't understand Chinese), but the premise concerns a part of the
system (the man doesn't understand Chinese). The argument is an instance of
"x isn't F, x is part of y, therefore y
isn't F", and so is invalid.[4] Thus
Palmer's "color room" argument fails to show anything whatever about
functionalism and experience.

[1] Palmer cites Wittgenstein as a supporter,
but I think the reverse is true: the view Palmer holds is one that Wittgenstein
argued against. Frege--the inventor of modern logic and one of the founders of
analytical philosophy--is a much better candidate (see especially 1918/1988,
and also 1884/1980, §26, where Frege uses the dual system analogy of the
target article (sect. 2.3 paras. 11-12)).

[2] Stalnaker draws a helpful analogy with Von
Neumann-Morgenstern utility theory, which assigns utility scales to people that
can only be compared intrapersonally, not interpersonally.

[4] Searle's response is to let the man perform
all the symbolic manipulations in his head, but this appeals to the inference
pattern "x isn't F, y is part of x, therefore
y isn't F", which is also invalid.